Marked Carbine Sling

I recently picked up this khaki carbine sling for a reasonable price; nice condition and no real issues. I hadn't unhooked the "Lift the Dot" until I had it home, and then opened it and found the marking "S.M. Co." over "1943". It's my first sling that has any manufacturer's marking on it. I believe it to be correct after looking at other examples online, but some of the comments say that this marking is "rare." I paid $45 and it's not for sale, but I would appreciate knowing if the marking is rare and, if so, what would be a reasonable price for something like this.

G-S Overmarked with S.M.C. is a Garco sling which was over inventoried as Standard Products lost its contract (assumption) and sold to Sturges Manufacturing Co.

One of the problems is for years I and everybody else based upon my sling research have always assumed S equals Schlegel. But since Schlegel has had different S markings, along with Standard Products (S-S2), I now think there is a small chance the S could be another maker like Springfield Leather Goods, or Charles Sorin Company. I doubt it is Sturges. Small chance, but nothing that can be confirmed yet.